Chemical vapor deposition is a thin film deposition technique about using a method of depositing a solid product onto a chip surface from reactants by a chemical reaction in a reactor. The reactants are usually gas reactants. After decades of developments, the chemical vapor deposition has become the most important and the main deposition method in the semiconductor manufacturing process for depositing a thin film on the semiconductor elements, such as conductors, semiconductors, and dielectric materials.
The key equipment of the facilities for the chemical vapor deposition is the reactor, and a thin film is deposed onto a substrate therein. However, according to the relevant application, scopes, the designs for chemical vapor deposition reactors might be various. A Hydrogen Vapor Phase Epitaxy reactor, HVPE reactor, is one of the popular chemical vapor decomposition reactors.
The conventional HVPE reactors for growing the compound semiconductors of IV and III–V groups of the periodical table and their alloys are well-known in the industry. These reactors can be divided into three main groups according to their geometrical features. The three main groups are respectively HVPE reactors with horizontal geometry of gas flow (HG HVPE reactors), HVPE reactors with vertical geometry of gas flow (VG HVPE reactors), and HVPE reactors with closed shower head (SH HVPE reactors).
Please refer to FIG. 1, which shows a structural diagram of a prior HG HVPE reactor. As shown in FIG. 1, the HG HVPE reactor includes a horizontal tube 11, a horizontal reagent gas flow 12, a substrate 13, and a gas heater 14. A hydride thin film is deposited on the substrate 13 through a reaction of the horizontal reagent gas flow 12 in the HG HVPE reactor. The relevant structures and features of HG HVPE reactors are disclosed in U.S. Pat. Nos. 6,176,925, 6,177,292, 6,179,913 and 6,350,666.
The disadvantages of above-mentioned HG HVPE reactors include: 1. It's difficult to obtain a high efficiency of gas utilization and high growth uniformity of the thin film simultaneously. 2. In order to avoid the temperature gradients inside the horizontal tube 11, a big gas heater 14 with high power consumption is always necessary. 3. Because it is difficult to control the temperature difference between the inside walls of the horizontal tube 11 and the substrate 13, a deposition material is always formed on the inside walls of the HG HVPE reactor. 4. Because of the long thermal relaxation time and the changes of the gas flow rate, a Quantum Well structure, QW structure, is unable grown. 5. It is difficult to control and model the growth processes of the thin film due to the low symmetry of the HG HVPE reactor.
Please refer to FIG. 2, which shows a structural diagram of a prior VG HVPE reactor. As shown in FIG. 2, the VG HVPE reactor includes a vertical tube 21, a vertical reagent gas flow 22, a substrate 23, and a gas heater 24. A hydride thin film is deposited on the substrate 23 through a reaction of the vertical reagent gas flow 22 in the VG HVPE reactor. The relevant structures and features of VG HVPE reactors are disclosed in U.S. Pat. Nos. 5,980,632 and 6,086,673.
The disadvantages of above-mentioned VG HVPE reactors include: 1. The growth uniformity of the thin film is not yet ideal enough. 2. In order to avoid the temperature gradients inside the vertical tube 21, a big gas heater 24 with high power consumption is still necessary. 3. Because it is still difficult to control the temperature difference between the inside walls of the vertical tube 21 and the substrate 23, a deposition material is always formed on the inside walls of the VG HVPE reactor. 4. Because of the long thermal relaxation time and the changes of the gas flow rate, a Quantum Well structure, QW structure, is either unable grown.
Please refer to FIG. 3, which shows a structural diagram of a prior SH HVPE reactor. As shown in FIG. 3, the SH HVPE reactor includes a horizontal tube 31, a vertical reagent gas flow 32, a substrate 33, a gas heater 34, and a shower-type head 35. A hydride thin film is deposited on the substrate 33 through a reaction of the vertical reagent gas flow 32 in the SH HVPE reactor. The SR HVPE reactor further includes a horizontal gas flow 36 as a buffer gas. The relevant structures and features of SH HVPE reactors are disclosed in U.S. Pat. No. 4,574,093.
The disadvantages of above-mentioned SH HVPE reactors include: 1. The shower-type head 35 is a non-technological design, so that the shower-type head 35 is difficultly fabricated. 2. Because it is difficult to control the temperature difference between the inside walls of horizontal tube 31 and the substrate 33, deposition materials are always formed on the inside walls of the SH HVPE reactor and the shower-type head 35.
As above-mentioned, a HVPE reactor with the abilities of high efficiency of gas utilization and high growth uniformity of thin film being able to avoid the erroneous deposition is worthy for the relevant industries.
Because of the technical defects described above, the applicant keeps on carving unflaggingly to develop a “CHEMICAL VAPOR DEPOSITION REACTOR”.